The present invention is directed to a membrane filter plate for a filter press comprising a carrier plate, at least one membrane arranged on a side of the carrier plate and being provided with distancing cams or spacing ribs for the placement of filter cloth or the like. The membrane filter plate also includes a sealing edge frame that surrounds the carrier plate and the membrane and connects these to one another in a solvent-tight arrangement.
U.S. Pat. No. 4,832,840, whose disclosure is incorporated by reference, and European Patent 00 81 715 both disclose a membrane filter plate for a filter press which comprises a carrier plate, at least one membrane arranged on one side of the carrier plate and provided with distancing cams or spacing ribs for the spacing of a filter cloth or the like from the membrane and includes a sealing edge frame that surrounds the carrier plate and the membrane and connects these to one another in an essentially solvent-tight arrangement. The carrier plate has circumferential surfaces which surround a recess portion and coact with circumferential surfaces of the edge frame which are parallel to the center plane of the plate and define the distance of the membrane plane in an unstressed, normal position from the center plane. The seating surface of the carrier plate facing toward the membrane is fashioned to extend from the connecting line of the membrane to the sealing edge frame, essentially parallel at first to the center plane of the carrier plate to provide desired bending lines for the filtration phase and, respectively, pressing phase and then extends obliquely at an angle of about 15.degree. toward said center plane of the carrier plate and then parallel to the center plane of the carrier plate over essentially the entire central region of the carrier plate.
During the re-pressing process of these prior art devices, the membrane shapes the filter cake and then proceeds on a path that is determined by the filter cake. This path is undefined. It has also been shown that it is not possible to observe a specific membrane path, even given an involved machine control. Since the carrier is usually combined with a chamber plate, the membrane traverses the full path in the extreme case and the repressing pressure presses it against the edges of the carrier plate edge and of the chamber plate. This then leads to a tearing of the membrane.